Sand treating system and method



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BYRON M. BiQD, ALBERT C. QICHAQDSON, lam/4M.

Oct. 5, 1943. B.'M. BIRD SAND TREATING SYSTEM AND METHOD Filed Dec. 4,1940 SAND TREATING SYSTEM AND METHOD Filed Dec. 4, 1940 3 Sheets-Sheet 2CLASSlFlER SCIZUBBEE KNOCKOUT f/vl/fA/roes,

BYRON M. BIQD. ALBEQT CLDmHAQDsON.

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3 Sheets-Sheet S B. M. BIRD SAND TREATING SYSTEM AND METHOD Filed Dec.4, 1940 Oct. 5, 1943.

DYQON M. B121), ALBEQT QElCHAQDSON.

iatented Oct. 5, 1943 SAND TREATING SYSTEM AND METHOD Byron M. Bird,Columbus, Ohio, assignor to The Jeffrey Manufacturing Company, acorporation of Ohio Application December 4,1940, Serial No. 368,524

6 Claims.

This invention relates to apparatus for and a method of treating sand tocondition, or recondition, it for use as foundry sand, either in. themaking of mold cores or as green moldin sand.

An object of the invention is to provide improved apparatus and animproved method as above outlined.

Another object of the invention is to provide a practical method of andapparatus for treating or reconditioning used core sand, such as oilcore sand, so that it can be used again.

Another object of the invention is to provide a method of and apparatusfor treating molding sand, either new or used, so that it will be ofuniform consistency and thus make uniformly good cores or molds.

Another object of the invention is to provide a method of and apparatusfor treating molding sand involving scrubbing or cleaning thereof toremove adhering foreign matter, such as spongy carbon, scale or otherforeign matter while the sand is in a bath of water.

Other objects of the invention will appear hereinafter, the novelfeatures and combinations being set forth in the appended claims.

In the accompanying drawings,

Fig. 1 is a plan view of a system comprising my invention which may beemployed to carry out the method of my invention;

Fig. 2 is a combination sectional and elevational view of the systemtaken on the line 22 of Fig. 1 looking in the direction of the arrows;

Fig. 3 is a combination sectional and elevational view of the system ofmy invention taken on the line 3-3 of Fig. 1 looking in the direction ofthe arrows;

Fig. 4 is a sectional view taken on the line 44 of Fig. 1 of thedrawings looking in the direction of the arrows;

Fig. 5 is a sectional view taken on the line 5-5 of Fig. 1 looking inthe direction of the arrows;

Fig. 6 is a plan view showing the upward current classifier which I haveused;

Fig. 7 is a sectional elevational view of the classifier of Fig. 6; and

Fig. 8 i a flow diagram of the system and method.

My method and system relates particularly to the treatment of used coresand, such as oil core sand, so that the sand may be substantially freeof foreign matter and thereby restored to its original condition or acondition which may be even superior to its original condition. Whilethis is the principal characteristic of my invention,

it is also'to be understood that it may be used to treat'ordinarymolding sand which has been used, or it may be used to treat originalsand which contains some impurities or foreign mat ter thereby toimprove its quality for use. either in the making of sand cores or foruse as green molding sand.

With respect to the principal feature of my invention, namely thetreating of used core sand so that it may be used again, it may bepointed out that core sand when once used tends o form a coating orouter layer of spongy carbon which is apparently due primarily to thefact that the bonding agent such as oil, molasse or other material tendsto carbon under the heat of the casting and this spongy coating or layerof carbon precludes the satisfactory reuse of the sand except that insome cases it has been used in relatively small quantities with newsand. My improved method and the apparatus which I provide has resultedin great saving of used core sand because it has been found that bytreating or reconditioning said core sand in accordance with myinvention all or substantially all of the original sand is recovered tobe used again, and this process of recovery can be carried onindefinitely because the quality of the sand appears to improve ratherthan degenerate by virtue of the reconditioning or retreating process.

in the accompanying drawings, I have illustrated one form of apparatuswhich may be employed to carry out my improved method, it beingunderstood of course that numerous modifications of the apparatus may bemade.

Referring particularly to Figs. 1 and 2 of the drawings, there is seenat II a knockout grating upon which the used sand, that is core sand orgreen sand as the case may be or even new sand which is to be treated,is received. In the case of used core sand it will be knocked out of thecastings by any well-known means such as a casting vibrator and-fall onthe grating Ill. The grating I0 is of a large mesh, for example theopenings may be as large as'2" by 4", and thus practically allof thesand, even use core sand, will freely pass through it and any largeparticles which do not pass through can be easily broken up so that theydo pass through.

Below the grating I Us a receiving hopper II which catches the sand anddirects it to a vibratory feeder 12 which may be of the electromagnetictype such as those known in the art as the Traylor Feeders manufacturedby The Jeffrey Manufacturing Company of Columbus, Ohio. The feeder I:when energized will feed 2 thesand to a belt conveyor It by which thesand is conveyed to a delivery chute I4 which feeds a swing hammercrusher l5. The conveyor l2 preferably has a magnetic pulley 16 whichattracts any iron which is delivered to chute l4 and causes it to stayon the belt of conveyor 42 until it is scraped off into an irondischarge chute ll which directs'it to a receptacle l8. The swing hammercrusher l5 breaks up the chunks ofmaterial without appreciably reducingthe size of any of the sand grains individually thus tending to freeeach sand grain of other adhering sand grains and thus exposing theentire surface of each grain of sand to be treated as hereinafterdescribed.

Swing hammer crusher l5 discharges onto a belt conveyor I9 which conveysthe sand to the boot of an elevating conveyor into which it discharges.The conveyor I9 preferably has a magnetic pulley 2| to catch any ironwhich is not removed by the magnetic pulley I6 and discharge it by wayof chute 22 into receptacle 29. The elevating conveyor 29 discharges thesand into a surge bin 24 which compensates for any variations in therate of feed of the sand to it to insure continuous operating of theequipment which follows the surge bin.

The surge bin 24 has a hopper-like bottom in which is mounted a screwconveyor 25 which conveys the material into a rotary pebble mill 25 orother scrubbing device. Water is fed to the pebble mill 25 by way ofpipe 21 having a control valve 28. As hereinafter pointed out morecompletely the pebble mill 26 is not used as a mill in the sense that itgrinds the sand, but is used as a scrubber to free the sand grains offoreign matter.

In the practice of my invention the sand to be treated is preferablycontinuously fed to the pebble mill 25 and also continuously fedtherefrom. This pebble mill is of the rotating type and its function isto scrub the individual particles of sand toremove the adhering coatingof foreign matter, such as spongy carbon, or any scale which may beattached to the sand particles. It is also effective to separate anyadhering grains of sand which have not been previously separated by theswing hammer crusher I5. This scrubbing action takes place in a bath ofwater which is preferably maintained at roughly a 25% solution ofwater'and a continuous scrubbing action has been found effectiveparticularly in a bath of water to remove all foreign material from thesand grains thereby conditioning them to the most desirable conditionpossible.

I have found from experiment that where an 011 core sand is beingretreated, the pebble mill 25 preferably employs steel punchings as aloose material to scrub the sand. In practice I have .used punchings ofthe size by 54; which moval of any large particles, this screen being afairly flne screen. It is particularly effective to remove particles ofcoke which are placed in sandcoresasiswellknowntothoseskilledin thefoundry art, which coke tends to float on the liquid in the pebble mill26 and is often of considerably larger size than the sand grains andthus is easily removed by the screen 29.

This foreign matter which is removed by the 5 screen 29 is discharged byway of chute 20 into a sludge tank 3! provided with scraper conveyormechanism 22 for removing the settled sludge a hereinafter describedmore completely.

The grains of sand as well as the foreign matter such as carbon whichhas been removed therefrom will pass through the screen cloth of screen29 where it is received by a hopp r-like structure and directed to anupward current classifler 22, or other type of gravity separator such asa jig of the type well-known in the minins or coal cleaning art. In thisinstallation the upward current classifier is preferred because of itssimplicity and cheapness.

The structure of the upward current classifier 20 which I have employedwith satisfactory results is shown particularly in Fig. 6 and 7 of thedrawings. This classifier comprises a container 24 having three bottomcells 25, and 21 supplied with water from a pipe 29 through individual25 control valves 29, 40 and 4|. Above the cells 25, 38 and 31 is aperforated plate 42 which slopes downwardly over the cells 25 and 25 butis substantially horizontal above the cell 21. Formed as substantialcontinuations of the cells 30 25, 36 and 31 and directlyabove each ofthem respectively are cells or compartments 42, 44 and 45 provided withoverflow weirs 45, 41 and 48 over which the liquid flows into receivingcompartments 49, 50 and SI respectively.

By reference to Fig. 6 of the drawings it will also be seen that thecell or compartment 43 has an extension 52 which first receives themixture of water, sand grains and foreign matter which passes throughthe screen 29. The function of 40 the upward current classifier 22 is ofcourse to effect a separation of the pure sand grains from the foreignmatter. In operation the mixture from the screen 29 flows into theextension 52 and into cell or compartment 43. The upwardly flowingcurrent which flows through pipe 24, valve 29 and bottom cell 35 andthence upwardly through cell or compartment 42 has a relatively lowvelocity; and so it is effective to classify the sand and foreign matterso that the heavy sand grains will move downwardl against the upwardlyflowing water while the spongy carbon and other foreign matter, whichhasa much lower specific gravity than sand. together with any very finematerial, and slime will flow over the weir 45 and into the receivingcompartment 49 from where it flows by pipe 52 (see Fig. 1) to the sludgesett i g tank 2 i It is thus evident that all foreign matter, slime andcarbon, will be removed by the upward current classifier in compartment42 and delivered to the sludge tank 2| where it will settle to thebottom and be removed by the scraper conveyor 22 up the inclined wallthereof as clearly illustrated at 54 in Fig. 3 of the drawings. As abovementioned, the sand grains which are the desired size, that is, all ofthem except the very fine ones, due to their high specific gravity willaccumulate on the plate 42 since they move downwardly in the cell 42,and since they are maintained in a continuous agitation b the waterflowing upwardly through the plate 42 they will slide downwardly alongsaid plate 42. The valve 40 is so adjusted that the upwardly flowingcurrent flows at a higher rate therethrough than 75 through the cell 25,and consequently the water through cell 44 flows at a higher rate thanthat through cell 43. This is effective to carry over the smallerparticles of sand and in one typical installation the sand from 120 meshto 70 mesh is carried over in this compartment flowing over the weir 4'!to receiving compartment 50. The larger sand grains continue to movedownward to.a position above cell 31 through which the water flowsupwardly at a still higher rate than that through cells-35 and 35, andconsequently the sand is preferably carried off through compartment orcell 45 over weir 45 into receiving compartment 5|. In other words, thetwo compartments 44 and 45 are primarily for obtaining two differentsize ranges of sand grains, and in many installations this separationwill not be necessary 7 or even desirable in which case atwo-compartment upward current classifier will be used, the

first compartment to remove the very fine sand which is not fed forreuse, the slimes, the carbon and any other foreign matter, the cleanedsand all being removed in the second compartment. If a jig isused, thesand of course will form on the bottom stratum, and all other materialsuch as the fines, slime, carbon and foreign matter will be dischargedover the weir as the low gravity material and will be conveyed to thesludge tank.

In the system disclosed I have shown apparatus for separating thereconditioned sand into two size ranges which are subsequently separablydewatered and dried. This separation and separate drying is not at allessential to my system or method in its broader aspects, but undercertain conditions may be desirable in case two different size ranges ofsand are desired.

Referring particularly to Fig. lot the drawings it will be seen that thesand and water delivered to receiving compartment 55 flow by way of pipe55 to an elevating dewatering scraper conveyor 55, and the sand andwater delivered to receiving compartment 5! flow by way of pipe 51 to anelevating dewatering scraper conveyor '58. The water which accumulatesin the bottom of the conveyors 55 and 55 is recirculated by a pump 59being delivered to the system and used by the upward current classifier33 and/or the pebble mill 25. r 7

Referring to Fig. 2 of the drawings, it will be seen that each of theelevating scraping conveyors 55 and 55 ha an upwardly inclined portionwhich insures complete dewatering-of the sand, that is, the removal ofall free flowing water, and this sand is then delivered to chutes 55 and5| from conveyors 55 and 58, respectively, by which it is directed torotary dryers 52 and 53, respectively. These rotary dryers 52'-and 53are of-well-known construction and briefly described comprise rotarycylinders which slope slightly downwardly from the receiving end at therear to the discharge end at the front, the interior walls of which areprovided with projections which lift the material to be dried, which inthis case is wet sand, and let it fall through a heated atmosphereprovided by a gas burner, that associated with the dryer 52 beingindicated at 54, which extends into the front end thereof and shoots aflame of burning gas into the dryer.

An exhaust gas fan means 55 is shown associated with the dryer 52, therebeing similar exhaust gas fan means associated with the dryer 53 toremove the exhaust gas which collects moisture delivered from the'sandin the process of drying the sand and delivers it outside the buildingwhich contains the equipment.

As illustrated particularly in Fig. 5 of the drawings, at its forwardend the dryer 52 has a'discharge chute 55 which delivers the dried sandonto a collecting belt conveyor 51. Dryer 53 also discharges onto thebelt conveyor 51 or, if desired, it may discharge onto another belt. Inthe first instance there will be a mixing of the sands delivered by thedryers 52 and 53 if they are operating simultaneously, while in thesecond instance such a mixing will not take place. It is of coursepossible to operate alternately the dryers 52 and 53 andthus maintaintheir productionsseparate by discharging from only one of them at a timeonto the single belt 51.

As best illustrated in Fig. 4 of the drawings, the belt 51 delivers thedried into the boot of an elevating conveyor 58 which elevates it anddelivers it to a distributing belting v conveyor 59 by which it may bedistributed to any one of three hoppers 10, ll and l2. s The bin intowhich the sand on distributing conveyor 59 discharges may be governed bycontrollable discharge plates 13 and 14. The green sand ready for reuseis thus stored in the bins 10, H and i2, and it may be separatedaccording to size into one or more of said bins if desired. From any ofthe bins 15, ii and 12 the reconditioned sand may be obtained for use byway of discharge hopper and chute mechanism, one of which -isillustrated at 15 associated with the bin 10 in Fig. 3 of the drawings.

In the operation of the mechanism comprising my invention with theconsequent carrying out of the method of my invention, the sand to betreated or retreated, be it used core sand, used foundry sand or newsand, any one of which may have foreign matter therein, is firstreceived by the grating [0 which of course keeps large particles, suchas castings, core flasks and the like in their proper place, from whichthe sand is conveyed to the swing hammer crusher l5, the metal beingremoved at least in part before the sand to be treated is delivered tosaid swing hammer crusher. Said crusher I5 is effective to break up thesand into individual grains, at least to a large extent. From thecrusher IS the sand is conveyed to surge bin 24, any iron passingthrough the crusher being removed by the magnetic pulley In the surgebin 24 the sand to be treated which may be called the impure sand is fedto the scrubbing device which in this case is a pebble mill 25 to whichsuificient water is fed to form a bath for the sand, an approximately 25solution of water having been found desirable.

Within the pebble mill 25 a thoroughscouring action is performed uponthe individual sand grains, and if any sand grains tend to adhere toeach other they will be separated during the process of this scouringaction. The scouring or scrubbing action will remove any adheringparticles of carbon or foreign matter from the sand grains thusconditioning them for future separation. This mixture of material, thatis, water and sand and foreign matter, will have a very high specificgravity. A light material, such as coke particles which are presentbecause of the fact a sand grains, coke particles or other largeparticles of foreign matter and small particles of carbon, scale orother foreign matter. The larger partiand reconditioned sand.

cles will be removed by the screen 2! and delivered to'the sludge tankII while the small particles with the water pass through said screen IIand into the upward current classifier 33. This classifier will act aswas described in detail above, first to separate the slimes, fine sand,carbon and other foreign matter, and deliver it to the ludge tank II.The pure sand is thereafter delivered into two sizes in the system andmethod disclosed, whereas in other systems and methods within myinvention it will be delivered only as a single size of clean sand, forsubsequent drying and storing. In the system and method disclosed onesize range of sand, for example 70 mesh to 120 mesh, is delivered to thedewatering conveyor 56 and another size range of sand, for example, '70mesh plus to dewatering conveyor 58. The dewatering conveyors i6 and 58are effective to reduce the water content of the clean sand appreciably,for example, to approximately 20%, and this dewatered but wet sand isdelivered by chutes 60, 6| to dryers 62, it where it is dried to acompletely satisfactory state of dryness and delivered to the conveyor61 which then delivers it to the elevating conveyor 68, thence todistributing conveyor 69 and other storage bins 10, II and 12, or anyone of them as desired. If desired, each of the dryers 62, it may have abelt conveyor comparable to the single conveyor 61 and a separateelevating conveyor comparable to the elevating conveyor 88 which maydeliver it into a separate storage bin instead of the three storage binsI0, H and 12.

Obviously those skilled in the art may make various changes in thedetails and arrangement of parts without departing from the spirit andscope of the invention as defined by the claims hereto appended, and Itherefore wish not to be restricted to the precise construction hereindisclosed.

Having thus described and shown an embodiment of my invention, what Idesire to secure by Letters Patent of the United States is:

1. The method of treating used foundry sand, comprising scrubbing thesand in a liquid bath to separate pure sand from foreign matter,screening the wet sand and foreign matter in remove foreign matter oflarge size, treating the screenings by an upward flow of water toproduce products of usable sand and foreign matter, directing theseparated products along different paths, and drying the usable sand.

2. The method of treating sand, comprising scrubbing the sand in aliquid bath to separate pure sand from foreign matter, screening the wetsand and foreign matter to remove foreign matter of large size, treatingthe screenings by an upward current of water to produce products ofusable sand and foreign matter, and directing the separated productsalong different paths.

3. The method of treating used foundry sand, comprising scrubbing thesand in a liquid bath to separate pure sand from carbonized binderforeign matte treating the sand and foreign matter by an upward currentof water to produce products of usable sand and foreign matter, anddirecting the separated products along diiferent paths.

4. Apparatus for cleaning used foundry sand comprising means forcrushing large particles formed by adhering sand grains, scrubbing meanscomprising a rotary pebble mill having loose scrubbing material thereinfor removing adhering foreign matter from the sand grains, means forsupply g water to said scrubbing means, means for conveying the usedsand from said crushing means to said scrubbing means, means fed by saidscrubbing means for separating the sand grains from the foreign matter,means for drying the cleaned sand, and means for storing said cleanedsand.

5. Apparatus for cleaning used foundry sand including a rotary scrubberhaving loose particles therein to aid the scrubbing action on the saidgrains during rotation of said scrubber, means for supplying water tosaid scrubber, a screen positioned to receive material from saidscrubber and remove large particles of foreign matter, and an upwardcurrent gravity separator adapted to separate the clean sand from theforeign matter.

matter, and a gravity separator adapted to separate the clean sand fromthe foreign matter.

BYRQN M. BIRD.

